The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Duo Wang - One of the best experts on this subject based on the ideXlab platform.
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scattering of elastic waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix i sh case
International Journal of Solids and Structures, 1996Co-Authors: Yuesheng Wang, Duo WangAbstract:In Part I of this two-part paper, the scattering of SH waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix is investigated by using the wave function expansion method and singular integral equation technique. The debonding regions are modeled as multiple arc-shaped interface cracks with non-contacting faces. Expressing the scattered fields as the wave function expansions with unknown coefficients and considering the mixed boundary conditions, we reduce the problem to a set of simultaneous dual series equations. Then dislocation density functions are introduced as unknowns to transform these dual series equations to a set of singular integral equations of the first type which can be easily solved numerically by using the quadrature method of Erdogan and Gupta [Int. J. Solids Structures7, 1089–1107 (1972)]. The solution is valid for arbitrary values of KT0r0 (where KT0 is the wave number and r0 the inclusion radius) and arbitrary numbers and sizes of the debonds. Explicit solutions are obtained in two limiting situations: (i) the long wavelength limit (KT0r0 ≪ 1). In this case, the solution reduces to the quasistatic solution; (ii) the small debond limit with KT0r0 = O(1). This means the wavelength greatly exceeds the debond size and the solution is identical to that of a flat interface crack between a rigid half space and an elastic one subjected to static loading at infinity. If the debond is small and KT0r0 ≪ 1, the solution will give the results of a flat interface crack subjected to an incident SH wave. Finally, the numerical results of the dynamic stress intensity factors, the rigid body translations of the inclusion and the scattering cross-sections are presented for an inclusion with one or two debonds. The phenomenon of low frequency resonance discovered by Yang and Norris [J. Mech. Phys. Solids39, 273–294 (1991)] for an elastic inclusion with one debond is shown and its dependence upon the various parameters is discussed. The solution of this problem is relevant to ultrasonic nondestructive detection of debonding and is expected to have applications to the question of how dynamic loading can lead to growth of debonds [Norris and Yang, Mech. Mater.11, 163–175 (1991)].
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Scattering of elastic waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix-II. P and SV cases
International Journal of Solids and Structures, 1996Co-Authors: Yuesheng Wang, Duo WangAbstract:In Part I of this two-part paper, the scattering of SH waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix is investigated by using the wave function expansion method and singular integral equation technique. The debonding regions are modeled as multiple arc-shaped interface cracks with non-contacting faces. Expressing the scattered fields as the wave function expansions with unknown coefficients and considering the mixed boundary conditions, we reduce the problem to a set of simultaneous dual series equations. Then dislocation density functions are introduced as unknowns to transform these dual series equations to a set of singular integral equations of the first type which can be easily solved numerically by using the quadrature method of Erdogan and Gupta [Int. J. Solids Structures7, 1089–1107 (1972)]. The solution is valid for arbitrary values of KT0r0 (where KT0 is the wave number and r0 the inclusion radius) and arbitrary numbers and sizes of the debonds. Explicit solutions are obtained in two limiting situations: (i) the long wavelength limit (KT0r0 ≪ 1). In this case, the solution reduces to the quasistatic solution; (ii) the small debond limit with KT0r0 = O(1). This means the wavelength greatly exceeds the debond size and the solution is identical to that of a flat interface crack between a rigid half space and an elastic one subjected to static loading at infinity. If the debond is small and KT0r0 ≪ 1, the solution will give the results of a flat interface crack subjected to an incident SH wave. Finally, the numerical results of the dynamic stress intensity factors, the rigid body translations of the inclusion and the scattering cross-sections are presented for an inclusion with one or two debonds. The phenomenon of low frequency resonance discovered by Yang and Norris [J. Mech. Phys. Solids39, 273–294 (1991)] for an elastic inclusion with one debond is shown and its dependence upon the various parameters is discussed. The solution of this problem is relevant to ultrasonic nondestructive detection of debonding and is expected to have applications to the question of how dynamic loading can lead to growth of debonds [Norris and Yang, Mech. Mater.11, 163–175 (1991)].
Yuesheng Wang - One of the best experts on this subject based on the ideXlab platform.
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scattering of elastic waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix i sh case
International Journal of Solids and Structures, 1996Co-Authors: Yuesheng Wang, Duo WangAbstract:In Part I of this two-part paper, the scattering of SH waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix is investigated by using the wave function expansion method and singular integral equation technique. The debonding regions are modeled as multiple arc-shaped interface cracks with non-contacting faces. Expressing the scattered fields as the wave function expansions with unknown coefficients and considering the mixed boundary conditions, we reduce the problem to a set of simultaneous dual series equations. Then dislocation density functions are introduced as unknowns to transform these dual series equations to a set of singular integral equations of the first type which can be easily solved numerically by using the quadrature method of Erdogan and Gupta [Int. J. Solids Structures7, 1089–1107 (1972)]. The solution is valid for arbitrary values of KT0r0 (where KT0 is the wave number and r0 the inclusion radius) and arbitrary numbers and sizes of the debonds. Explicit solutions are obtained in two limiting situations: (i) the long wavelength limit (KT0r0 ≪ 1). In this case, the solution reduces to the quasistatic solution; (ii) the small debond limit with KT0r0 = O(1). This means the wavelength greatly exceeds the debond size and the solution is identical to that of a flat interface crack between a rigid half space and an elastic one subjected to static loading at infinity. If the debond is small and KT0r0 ≪ 1, the solution will give the results of a flat interface crack subjected to an incident SH wave. Finally, the numerical results of the dynamic stress intensity factors, the rigid body translations of the inclusion and the scattering cross-sections are presented for an inclusion with one or two debonds. The phenomenon of low frequency resonance discovered by Yang and Norris [J. Mech. Phys. Solids39, 273–294 (1991)] for an elastic inclusion with one debond is shown and its dependence upon the various parameters is discussed. The solution of this problem is relevant to ultrasonic nondestructive detection of debonding and is expected to have applications to the question of how dynamic loading can lead to growth of debonds [Norris and Yang, Mech. Mater.11, 163–175 (1991)].
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Scattering of elastic waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix-II. P and SV cases
International Journal of Solids and Structures, 1996Co-Authors: Yuesheng Wang, Duo WangAbstract:In Part I of this two-part paper, the scattering of SH waves by a rigid cylindrical inclusion partially debonded from its Surrounding Matrix is investigated by using the wave function expansion method and singular integral equation technique. The debonding regions are modeled as multiple arc-shaped interface cracks with non-contacting faces. Expressing the scattered fields as the wave function expansions with unknown coefficients and considering the mixed boundary conditions, we reduce the problem to a set of simultaneous dual series equations. Then dislocation density functions are introduced as unknowns to transform these dual series equations to a set of singular integral equations of the first type which can be easily solved numerically by using the quadrature method of Erdogan and Gupta [Int. J. Solids Structures7, 1089–1107 (1972)]. The solution is valid for arbitrary values of KT0r0 (where KT0 is the wave number and r0 the inclusion radius) and arbitrary numbers and sizes of the debonds. Explicit solutions are obtained in two limiting situations: (i) the long wavelength limit (KT0r0 ≪ 1). In this case, the solution reduces to the quasistatic solution; (ii) the small debond limit with KT0r0 = O(1). This means the wavelength greatly exceeds the debond size and the solution is identical to that of a flat interface crack between a rigid half space and an elastic one subjected to static loading at infinity. If the debond is small and KT0r0 ≪ 1, the solution will give the results of a flat interface crack subjected to an incident SH wave. Finally, the numerical results of the dynamic stress intensity factors, the rigid body translations of the inclusion and the scattering cross-sections are presented for an inclusion with one or two debonds. The phenomenon of low frequency resonance discovered by Yang and Norris [J. Mech. Phys. Solids39, 273–294 (1991)] for an elastic inclusion with one debond is shown and its dependence upon the various parameters is discussed. The solution of this problem is relevant to ultrasonic nondestructive detection of debonding and is expected to have applications to the question of how dynamic loading can lead to growth of debonds [Norris and Yang, Mech. Mater.11, 163–175 (1991)].
Amir Polak - One of the best experts on this subject based on the ideXlab platform.
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tracer diffusion from a horizontal fracture into the Surrounding Matrix measurement by computed tomography
Journal of Contaminant Hydrology, 2003Co-Authors: Amir Polak, Abraham S Grader, Rony Wallach, Ronit NativAbstract:Abstract The vertical diffusion of NaI solution from a horizontal fracture into and within the Surrounding Matrix was tracked and quantified over time using an artificially fractured chalk core (30×5 cm) and a second-generation X-ray computed tomography (CT) scanner. The different tracer-penetration distances imaged in the Matrix above and below the horizontal fracture are indicative of a greater tracer mass penetrating into the lower Matrix. The enhanced transport in the Matrix below the fracture was related to the Rayleigh–Darcy instability induced by the density differences between the heavier tracer solution in the fracture (1.038) and the distilled water that had initially resided in the Matrix. Our observations suggest that below the fracture, the tracer is propagated by an advection–diffusion process that is characterized by both higher rates and higher concentrations relative to its propagation by diffusion above the fracture. The experimental results suggest that the prediction of contaminant migration in a rock intersected by both vertical and horizontal (e.g. along bedding planes) fractures is difficult because of density effects that result in different solute-penetration rates.
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chemical diffusion between a fracture and the Surrounding Matrix measurement by computed tomography and modeling
Water Resources Research, 2003Co-Authors: Amir Polak, Abraham S Grader, Rony Wallach, Ronit NativAbstract:[1] A medical-based X-ray CT scanner was used to monitor the diffusion of NaI into the Matrix of a 20-cm-long, 5-cm diameter fractured chalk core. The core was retrieved from a core hole at a depth of 18.3 m and was artificially fractured along its axis using a Brazilian-like test. The NaI solution flowed continuously along the vertically oriented fracture and the transient lateral concentration distribution within the Matrix at different cross sections along the core was monitored by two-dimensional 2-mm-thick slices through the sample and an in-plan pixel resolution of about 0.25 mm. The lateral concentration distribution within the Matrix was characterized by a sharp decrease at a thin Matrix layer adjacent to the fracture/Matrix interface followed by diffusion-type concentration distribution elsewhere. This concentration variation suggests that a thin transition layer exists along the fracture/Matrix interface where the diffusion coefficient is higher than that of the bulk Matrix. The higher diffusion coefficient of the transition layer is possibly related to minifissures that develop when fractures are formed. After 6 days of tracer injection into the fracture inlet, distilled water was injected for 11 days, forming a reverse concentration gradient and back diffusion. A mathematical model that assumes diffusion within the Matrix and a linear concentration variation through the transition layer from its value in the fracture to its time-dependent value at the transition layer/Matrix interface was developed. Very good agreement was obtained between the predicted and measured concentrations during both the diffusion and back diffusion phases. Application of the model to a field site in the Negev desert, Israel, suggested that the rock Matrix that had been subjected to 20 year of contaminant diffusion would require more than 200 years before it would stop releasing contaminants into the intersecting fractures (a parabolic process). According to these calculations, remediation efforts based on clean water injection into the fractures are not feasible.
Ronit Nativ - One of the best experts on this subject based on the ideXlab platform.
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tracer diffusion from a horizontal fracture into the Surrounding Matrix measurement by computed tomography
Journal of Contaminant Hydrology, 2003Co-Authors: Amir Polak, Abraham S Grader, Rony Wallach, Ronit NativAbstract:Abstract The vertical diffusion of NaI solution from a horizontal fracture into and within the Surrounding Matrix was tracked and quantified over time using an artificially fractured chalk core (30×5 cm) and a second-generation X-ray computed tomography (CT) scanner. The different tracer-penetration distances imaged in the Matrix above and below the horizontal fracture are indicative of a greater tracer mass penetrating into the lower Matrix. The enhanced transport in the Matrix below the fracture was related to the Rayleigh–Darcy instability induced by the density differences between the heavier tracer solution in the fracture (1.038) and the distilled water that had initially resided in the Matrix. Our observations suggest that below the fracture, the tracer is propagated by an advection–diffusion process that is characterized by both higher rates and higher concentrations relative to its propagation by diffusion above the fracture. The experimental results suggest that the prediction of contaminant migration in a rock intersected by both vertical and horizontal (e.g. along bedding planes) fractures is difficult because of density effects that result in different solute-penetration rates.
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chemical diffusion between a fracture and the Surrounding Matrix measurement by computed tomography and modeling
Water Resources Research, 2003Co-Authors: Amir Polak, Abraham S Grader, Rony Wallach, Ronit NativAbstract:[1] A medical-based X-ray CT scanner was used to monitor the diffusion of NaI into the Matrix of a 20-cm-long, 5-cm diameter fractured chalk core. The core was retrieved from a core hole at a depth of 18.3 m and was artificially fractured along its axis using a Brazilian-like test. The NaI solution flowed continuously along the vertically oriented fracture and the transient lateral concentration distribution within the Matrix at different cross sections along the core was monitored by two-dimensional 2-mm-thick slices through the sample and an in-plan pixel resolution of about 0.25 mm. The lateral concentration distribution within the Matrix was characterized by a sharp decrease at a thin Matrix layer adjacent to the fracture/Matrix interface followed by diffusion-type concentration distribution elsewhere. This concentration variation suggests that a thin transition layer exists along the fracture/Matrix interface where the diffusion coefficient is higher than that of the bulk Matrix. The higher diffusion coefficient of the transition layer is possibly related to minifissures that develop when fractures are formed. After 6 days of tracer injection into the fracture inlet, distilled water was injected for 11 days, forming a reverse concentration gradient and back diffusion. A mathematical model that assumes diffusion within the Matrix and a linear concentration variation through the transition layer from its value in the fracture to its time-dependent value at the transition layer/Matrix interface was developed. Very good agreement was obtained between the predicted and measured concentrations during both the diffusion and back diffusion phases. Application of the model to a field site in the Negev desert, Israel, suggested that the rock Matrix that had been subjected to 20 year of contaminant diffusion would require more than 200 years before it would stop releasing contaminants into the intersecting fractures (a parabolic process). According to these calculations, remediation efforts based on clean water injection into the fractures are not feasible.
Nemkumar Banthia - One of the best experts on this subject based on the ideXlab platform.
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a study of some factors affecting the fiber Matrix bond in steel fiber reinforced concrete
Canadian Journal of Civil Engineering, 1990Co-Authors: Nemkumar BanthiaAbstract:With the objective of understanding the reinforcing mechanisms of fibers in steel fiber reinforced concrete, the bond between the fibers and the Surrounding Matrix is studied by conducting single f...
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A study of some factors affecting the fiber–Matrix bond in steel fiber reinforced concrete
Canadian Journal of Civil Engineering, 1990Co-Authors: Nemkumar BanthiaAbstract:With the objective of understanding the reinforcing mechanisms of fibers in steel fiber reinforced concrete, the bond between the fibers and the Surrounding Matrix is studied by conducting single f...